Many types of machines use an engine for motive power, and rely upon a radiator and an air circulation fan to assist in cooling the engine. The engine, radiator and fan are typically positioned within a housing that includes an air intake screen and an outlet opening. During normal operations, the fan draws air into the housing through the air intake screen, directs the air through the radiator and out of the housing through the outlet opening. In many types of applications, the machine may be working or traveling in a dirt and/or debris filled environment. As a result, materials such as dirt, insects, trash, leaves and the like can become lodged on the air intake screen. As material accumulates on the air intake screen, the effectiveness of the air circulation system, and hence the cooling capability of the associated radiator can be undermined.
One strategy for dealing with the accumulation of material on the radiator and air intake screen is taught in co-owned U.S. Pat. No. 6,750,623, which is entitled Reversible Automatic Fan Control System. In that reference, a fan control system periodically and automatically reverses the direction of the air flow system to dislodge accumulated materials from the radiator and air intake screen. After a brief purge cycle, the system automatically returns to its normal cooling operation and again reverses the air flow direction into its normal direction to circulate air from the air intake screen through the radiator and out of the outlet opening. While such an automated air circulation/purge cycle system can normally operate very effectively, and relieve an operator of manually monitoring and operating the fan in a purge cycle, the automated fan reversal system purging cycle can sometimes occur at an inopportune time.
Typically, the air circulation system will continue in its normal mode for some fixed duration, such as thirty (30) minutes, and then be followed by a brief purge cycle on the order of maybe thirty (30) seconds or less. This air circulation/purge cycling continues while the engine of the machine is running. In some instances, it may not be desirable for the purge cycle to occur, such as when a person may be in the vicinity of the air intake screen. In some machines, such as large landfill compactors and wheel loaders, the access path to the operator station actually crosses in front of the air intake screen. In other instances, a service point associated with the machine may be located in the vicinity of the air intake screen. Therefore, persons on an access path or at the service point could have debris blown onto them if the fan reverses direction to initiate a purge cycle.
The present disclosure is directed to one or more of the problems set forth above.